The present invention relates to the treatment of deposits forming obstructions in body passages, such as blood vessels, and particularly to the removal of such deposits by chemical dissolution. The invention also relates to other types of treatment of limited regions of a body passage wall.
It has previously been proposed to effect various treatments on isolated portions of the walls of body passages including, but not limited to, blood vessels. For example, certain materials, such as plaque, form deposits on blood vessel walls. These deposits can become sufficiently large to significantly impede the flow of blood, thereby creating a life threatening medical condition. In addition, when performing treatments associated with the removal of plaque, or the treatment of other conditions in blood vessels, it may be desired to bring a treatment material into contact with an isolated portion of a body passage wall for an extended period of time.
It frequently occurs that the location where treatment is to be performed is in close proximity to a side branch of the body passage. Unless such a side branch is blocked, the treatment agent brought into contact with the body passage wall will flow off via that side branch.
It has been proposed, as disclosed in U.S. Pat. No. 5,176,638, to isolate a body passage region by means of a catheter provided with two blocking balloons, or other blocking devices, which isolate a region to be treated from the remainder of the body passage. If the balloons of such a catheter system happen to be properly positioned relative to any adjacent side branches, the balloons can also act to block those branches.
However, with the devices previously disclosed, use is made of balloons which, upon expansion, are inflated essentially radially, and possibly circumferentially. Therefore, these balloons can act on a side branch which is not outside the treatment region only if the balloon is directly aligned with the side branch. If, on the other hand, the side branch is offset somewhat from the balloon and is located essentially within the treatment region, it cannot be blocked.